Roll bumper stabilizer bar links

ABSTRACT

A vehicle suspension is provided that includes a frame supporting a pair of laterally spaced apart suspension members pivotally supported on the frame and movable in a vertical direction. Each of a pair of wheel ends is supported respectively on one of the suspension members. A stabilizer bar is supported on the frame laterally between the suspension members. The stabilizer bar includes opposing ends each respectively proximate one of the suspension members. Each of a pair of resilient stabilizer bar links respectively interconnects one of the ends and one of the suspension members and transmits torsional force to the stabilizer bar in response to movement of the suspension members in the vertical direction during roll conditions. The links have first and second deflection rates during the roll condition with the first rate being less than the second deflection rate. The links transition from the first deflection rate to the second deflection rate and from the second deflection rate to an effective zero deflection rate.

This is a Divisional of U.S. patent application Ser. No. 10/143,289,filed May 10, 2002.

BACKGROUND OF THE INVENTION

This invention relates to a stabilizer bar for a vehicle suspensionsystem, and more particularly, the invention relates to stabilizer barlinks used to attach the ends of the stabilizer bar to a vehiclesuspension member.

Stabilizer bars are used in vehicle suspension systems to stabilize thevehicle laterally during vehicle turning and maneuvers in which thevehicle rolls side to side. In addition to stabilizing the vehicle, thestabilizer bar provides feedback to the vehicle operator regarding thestability of the vehicle during the turning maneuver. Providing a softfeel in which the vehicle rolls appreciatively during a turningmaneuver, the driver is made aware of the vehicle's instability therebyencouraging the driver to operate the vehicle more conservatively toprevent loss of control of the vehicle during the turning maneuver. Byway of contrast, a firm or hard feel provides the vehicle operator withfeedback that the vehicle is stable by rolling very little during theturning maneuver. In this manner, the vehicle operator may drive moreaggressively than desired causing the vehicle to suddenly lose tractionand spin out of control.

The roll feel provided by the suspension assembly is determined by thestiffness of the suspension springs, the stiffness of the stabilizer baritself, and the stiffness of the bushings used in the connections of thestabilizer bars and suspension members such as lower control arms. Theroll stiffness is typically selected to provide either a soft feel or afirm or hard feel depending upon the particular vehicle application andexpectation of the driver. It would be desirable to provide a variableroll stiffness and feedback to the driver during various rollconditions.

SUMMARY OF THE INVENTION AND ADVANTAGES

The present invention provides a vehicle suspension including a framesupporting a pair of laterally spaced apart suspension members pivotallysupported on the frame and movable in a vertical direction. Each of apair of wheel ends is supported respectively on one of the suspensionmembers. A stabilizer bar is supported on the frame laterally betweenthe suspension members. The stabilizer bar includes opposing ends eachrespectively proximate one of the suspension members. Each of a pair ofresilient stabilizer bar links respectively interconnects one of theends and one of the suspension members and transmits torsional force tothe stabilizer bar in response to movement of the suspension members inthe vertical direction during roll conditions. The links have first andsecond deflection rates during the roll condition with the first ratebeing less than the second deflection rate. The links transition fromthe first deflection rate to the second deflection rate and from thesecond deflection rate to an effective zero deflection rate.

Accordingly, the above invention provides a variable roll stiffness andfeedback to the driver during various roll conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention can be understood by referenceto the following detailed description when considered in connection withthe accompanying drawings wherein:

FIG. 1 is a perspective view of a vehicle suspension system;

FIG. 2 is a chart depicting the link deflection versus roll input forthe present invention stabilizer bar links;

FIG. 3 is a stabilizer bar link having a bushing with a variabledeflection rate;

FIG. 4 is an alternative bushing;

FIG. 5 is another stabilizer bar link of the present invention;

FIG. 6 is yet another stabilizer bar link of the present invention;

FIG. 7 is still another stabilizer bar link of the present invention;and

FIG. 8 is yet another stabilizer bar link of the present inventionhaving active control.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A vehicle suspension system 10 is shown in FIG. 1. The system 10includes a frame 12 that supports the suspension members including alower control arm 14 and an upper control arm 16. A knuckle 18 issecured between the lower control arm 14 and upper control arm 16. Aspring 20 may be arranged between the lower control arm 14 and the frame12. Wheel ends 22 are supported by the knuckles 18. Although a four-barsuspension arrangement is shown, it is to be understood that the presentinvention may be utilized with any suspension arrangement.

A stabilizer bar 24 is arranged laterally between the lower control arms14 on either side of the vehicle. The stabilizer bar 24 includes alateral bar portion 25 supported on the frame 12 by brackets 26. Thestabilizer bar 24 also includes arms 28 that are secured to the lowercontrol arms 14 by stabilizer bar links 30. The stabilizer bar links 30transmit the vertical inputs from the lower control arms 14 to thestabilizer bar 24 to realize stability to a vehicle during rollconditions and provide feedback to the vehicle operator indicative ofthe vehicle stability. The present invention provides a roll curve shownin FIG. 2 that provides at least a soft feel (shown by curve A), a firmfeel (shown by curve B), and a hard feel (shown by curve C).

The stabilizer bar link 30 includes a first end 32 and a second end 34defining a first connection 36 and a second connection 38. Each of theconnections may include a first resilient member 40 and second resilientmember 42 that are coaxial with one another that define a bushing. Thebushing includes a hole 44 for receiving a fastener that attaches thestabilizer bar link 30 between the lower control arm 14 and thestabilizer bar 24. The first resilient member 40 and second resilientmember 42 may be made out of a rubber material. The first resilientmember 40 may be softer than the second resilient member 42 such thatthe first resilient member 40 deflects greater than the second resilientmember 42. In this manner, the first resilient member 40 will begindeflecting first and provide a soft feel. The second resilient member 42will then begin to deflect after the first resilient member 40 hasdeflected and provide a firmer feel. Finally, the first resilient member40 and second resilient member 42 will no longer deflect and provide aneffectively zero deflection rate which provides a hard feel to thevehicle operator.

The bushing 46 shown in FIG. 4 may also be used with the stabilizer barlink 30 to provide a variable deflection rate. For example, the bushing46 includes arcuate apertures 48 arranged about the hole 44. The bushing46 will deflect until the arcuate apertures 48 become closed and theinner portion of the hole 44 engages the outer portion of the bushing 46to provide a firm feel. The bushing 46 will cease deflecting and providea hard feel to the vehicle operator.

Another stabilizer bar link arrangement is shown in FIG. 5. Thestabilizer bar link 30 includes a link 50 having flanges 52. Resilientmembers 54 are arranged about the lower control arm 14 and thestabilizer bar 24 to effectively sandwich the suspension member and barbetween the flanges 52. The fasteners 56 such as nuts are secured to thelink 50 to connect the stabilizer bar 24 to the lower control arm 14.The resilient members 54 adjacent to the lower control arm 14 andstabilizer bar 24 may have a first deflection rate, and the resilientmembers 54 adjacent to the flanges 52 may have a second deflection ratedifferent than the first deflection rate.

Another stabilizer bar link arrangement is shown in FIG. 6. Thestabilizer bar link 30 may include a rigid member 58 telescopicallyreceived within a housing 60. The housing 60 may be secured to thestabilizer bar 24 and the rigid member 58 may be secured to the lowercontrol arm 14. A first resilient member 62 and a second resilientmember 64 may be coaxially arranged relative to one another. The firstresilient member 62 and second resilient member 64 may be secured to oneanother and secured between the rigid member 58 and the housing 60. Thefirst resilient member 62 has a first deflection rate, and the secondresilient member 64 has a second deflection rate different than thefirst resilient member 62. The housing 60 may include a stop 65 to limitthe motion of the rigid member 58 to the housing 60.

The first stabilizer bar links 30 are shown in FIGS. 7 and 8. Referringto FIG. 7, the stabilizer bar link 30 may include a housing 66 having apiston 68 disposed therein. A rod 70 is secured to the piston 68 and maybe attached to the lower control arm 14. The housing 66 may be attachedto the stabilizer bar 24. The housing 66 defines a fluid cavity 72 thatis separated into a first chamber 74 and a second chamber 76 by thepiston 68. The housing 66 is filled with hydraulic fluid. An orifice 78may be arranged in the piston 68 to define a damping rate thatcorresponds to a first deflection rate. A first spring 80 and a secondspring 82 may be respectively arranged within the first chamber 74 andthe second chamber 76. The first spring 80 and the second spring 82define a second deflection rate.

Referring to FIG. 8, a magneto-rheological fluid stabilizer bar link 30is shown. The magneto-rheological fluid stabilizer bar link 30 includesa housing 84 having a piston 86 disposed therein with a rod 88 connectedto the piston 86. The housing 84 and rod 88 are connected between thelower control arm 14 and the stabilizer bar 24. The housing 84 defines afluid cavity 90 separated into a first chamber 92 and a second chamber94 by the piston 86. The piston 86 may include an orifice 96 forproviding damping. A coil 97 may be arranged about the housing 84 and isconnected to a controller 98. The controller 98 energizes the coil 97and creates a magnetic field about the housing 84 to change theviscosity of the magneto-rheological fluid thereby changing the fluidflow through the orifice 96. Accelerometers 100 and 102 are connected tothe controller 98 and provide lateral and forward/rearward acceleration.The controller 98 is programmed to selectively control the magneticfield produced by the coil 97 in response to the accelerometers 100 and102 to provide variable roll damping. In this manner an infinitelyvariable damping or deflection rate may be provided by themagneto-rheological fluid stabilizer bar link 30.

The invention has been described in an illustrative manner, and it is tobe understood that the terminology that has been used is intended to bein the nature of words of description rather than of limitation.Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

1. A vehicle suspension system comprising: a frame; a pair of laterallyspaced apart suspension members pivotally supported on the frame andmovable in a vertical direction; a stabilizer bar supported on the framelaterally between the suspension members, the stabilizer bar includingopposing stabilizer bar ends each respectively proximate to one of thesuspension members; and a pair of stabilizer bar links each respectivelyinterconnecting one of the opposing stabilizer bar ends and one of thesuspension members and transmitting a torsional force to the stabilizerbar in response to movement of the suspension members in the verticaldirection during a roll condition, each of the pair of stabilizer barlinks having a fluid with a viscosity that is selectively variable inorder to change a damping rate.
 2. The vehicle suspension systemaccording to claim 1, wherein each of the pair of stabilizer bar linksincludes opposing link ends, with one of the opposing link ends securedto one of the opposing stabilizer bar ends and the other of the opposinglink ends secured to one of the suspension members.
 3. The vehiclesuspension system of claim 2, wherein each of the pair of stabilizer barlinks includes a housing connected to one of the opposing link ends anda piston connected to the other of the opposing link ends, the housingdefining a fluid cavity containing the fluid, the piston disposed in thefluid cavity, the piston separating the fluid cavity into a firstchamber and a second chamber.
 4. The vehicle suspension system of claim3 wherein the piston includes an orifice fluidly connecting the firstchamber and the second chamber.
 5. The vehicle suspension system ofclaim 1 wherein the fluid is a magneto-rheological fluid
 6. The vehiclesuspension system of claim 5 further including an electromagnetic fieldsource for generating an electromagnetic field to control the viscosityof the magneto-rheological fluid.
 7. The vehicle suspension systemaccording to claim 1 wherein a controller is connected to a magneticsource cooperating with the fluid, the controller controlling themagnetic source in order to change the viscosity of the fluid.
 8. Thevehicle suspension system according to claim 7, wherein an accelerometeris connected to the controller to provide a vehicle rate of roll signalto the controller, the controller controlling the magnetic source tochange the viscosity of the fluid based upon the vehicle rate of rollsignal.
 9. A method of providing driver feedback during vehicle rollmaneuvers comprising the steps of: a) providing a stabilizer barattached to a suspension member by a stabilizer bar link, the stabilizerbar link having a fluid with a selectively variable viscosity; b)effecting a first viscosity of the fluid during a first vehicle roll;and c) effecting a second viscosity of the fluid during a second vehicleroll, the first viscosity greater than the second viscosity.
 10. Themethod of claim 9 wherein said steps b) and c) are performed by alteringa magnetic field in which the fluid is at least partially disposed. 11.The method of claim 10 further including the step of measuringacceleration and effecting the first viscosity of the fluid in said stepb) based upon the acceleration.
 12. The method of claim 11 wherein thesecond viscosity is effected in said step c) based upon theacceleration.
 13. A stabilizer bar link assembly comprising: a housinghaving a first connection area; a magneto-rheological fluid in thehousing; and a piston having a first end disposed within the housing anda second end having a second connection area.
 14. The stabilizer barlink assembly of claim 13 wherein the housing defines a fluid cavitydivided into a first chamber and a second chamber by the piston.
 15. Thestabilizer bar link assembly of claim 14 wherein the piston includes anorifice providing fluid communication between the first chamber and thesecond chamber.
 16. The stabilizer bar link assembly of claim 15 furtherincluding a magnetic source generating a magnetic field in which thefluid is at least partially disposed.